Unfortunately, Clang did not have support for "sp" as a global register
definition, and was crashing after the addition of current_stack_pointer.
This has been fixed in Clang 15, but earlier Clang versions need to
avoid this code, so add a versioned test and revert back to the
open-coded asm instances. Fixes Clang build error:
fatal error: error in backend: Invalid register name global variable
Fixes: 200ed341b864 ("mips: Implement "current_stack_pointer"")
Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Link: https://lore.kernel.org/lkml/YikTQRql+il3HbrK@dev-arch.thelio-3990X
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Yanteng Si <siyanteng01@xxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
v1: https://lore.kernel.org/lkml/20220309204537.390428-1-keescook@xxxxxxxxxxxx
v2: - adjust Clang version (Nathan)
---
arch/mips/Kconfig | 2 +-
arch/mips/include/asm/thread_info.h | 2 ++
arch/mips/kernel/irq.c | 3 ++-
arch/mips/lib/uncached.c | 4 +++-
4 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 3f58b45fc953..0dae5f1e61cc 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -4,7 +4,7 @@ config MIPS
default y
select ARCH_32BIT_OFF_T if !64BIT
select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
- select ARCH_HAS_CURRENT_STACK_POINTER
+ select ARCH_HAS_CURRENT_STACK_POINTER if !CC_IS_CLANG || CLANG_VERSION >= 140000
select ARCH_HAS_DEBUG_VIRTUAL if !64BIT
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_KCOV
diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index 4463348d2372..ecae7470faa4 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -69,7 +69,9 @@ static inline struct thread_info *current_thread_info(void)
return __current_thread_info;
}
+#ifdef CONFIG_ARCH_HAS_CURRENT_STACK_POINTER
register unsigned long current_stack_pointer __asm__("sp");
+#endif
#endif /* !__ASSEMBLY__ */
diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
index fc313c49a417..5e11582fe308 100644
--- a/arch/mips/kernel/irq.c
+++ b/arch/mips/kernel/irq.c
@@ -75,8 +75,9 @@ void __init init_IRQ(void)
#ifdef CONFIG_DEBUG_STACKOVERFLOW
static inline void check_stack_overflow(void)
{
- unsigned long sp = current_stack_pointer;
+ unsigned long sp;
+ __asm__ __volatile__("move %0, $sp" : "=r" (sp));
sp &= THREAD_MASK;
/*
diff --git a/arch/mips/lib/uncached.c b/arch/mips/lib/uncached.c
index f8d4ca046c3e..f80a67c092b6 100644
--- a/arch/mips/lib/uncached.c
+++ b/arch/mips/lib/uncached.c
@@ -40,7 +40,9 @@ unsigned long run_uncached(void *func)
register long ret __asm__("$2");
long lfunc = (long)func, ufunc;
long usp;
- long sp = current_stack_pointer;
+ long sp;
+
+ __asm__("move %0, $sp" : "=r" (sp));
if (sp >= (long)CKSEG0 && sp < (long)CKSEG2)
usp = CKSEG1ADDR(sp);
--
2.32.0
